STUDY OF COHERENT ANOMALIES AND CRITICAL EXPONENTS BASED ON HIGH-LEVEL CLUSTER-VARIATION APPROXIMATIONS

The coherent-anomaly scaling property of the susceptibility for the Ising model is investigated using the Tanoji (a Chinese character which means a rice field) and cube cluster-approximations in the cluster-variation method on the square and simple cubic lattices, respectively. Estimates of the critical temperature and critical exponent are improved considerably by the inclusion of these high-level cluster-variation approximations in the coherent-anomaly extrapolation. It is also found that the dimen-sionality of the basic cluster is sensitive to the evaluation of critical exponents in higher dimensions. © 1990, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.